import paramiko

pkey = paramiko.RSAKey.from_private_key_file('id_rsa_32')
ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())

ssh.connect(hostname='10.37.253.32',port=22,username='root',pkey=pkey)

stdin,stdout,stderr=ssh.exec_command('free -m')
print(stdout.read().decode())
ssh.close()